南亚热带森林演替植物幼苗生态位适应度模拟

适应度和生态位适应度既有相似性也存在区别,该文在综述两者概念的基础上,利用生态位中心、实际生态位和生态位宽度构建生态位适应度,分析两者存在的关系.结果发现生态位适应度和适应度具有一定的相关性,幼苗的生理特性可以用于表征物种在演替过程中的适应度,但是生态位适应度的动态提前于适应度的动态;同时利用限制因子构建的生态位适应度模型可以了解演替过程中影响物种演替的限制因子.该文的研究提供了一种利用物种生理特性定量研究演替过程中物种适应度动态的方法.      

Opposing effects of native and exotic herbivores on plant invasions

Exotic species are widely assumed to thrive because they lack natural enemies in their new ranges. However, a meta-analysis of 63 manipulative field studies including more than 100 exotic plant species revealed that native herbivores suppressed exotic plants, whereas exotic herbivores facilitated both the abundance and species richness of exotic plants. Both outcomes suggest that plants are especially susceptible to novel, generalist herbivores that they have not been selected to resist. Thus, native herbivores provide biotic resistance to plant invasions, but the widespread replacement of native with exotic herbivores eliminates this ecosystem service, facilitates plant invasions, and triggers an invasional "meltdown."     

基于叶片特征的计算机辅助植物识别模型

植物的数量分类的主要依据是植物的外观特征，通过提取大量特征数据进行聚类分析获得结果。传统做法都是手工测量采集原始数据，效率较低。由于外观特征都可以以数字图片方式获得，通过计算机图像处理分析等技术采集数据并做聚类分析将大大提高效率。关键问题在于特征自动分析和获取，以植物叶片为例，阐述了如何提取大小、叶形及叶缘特征的方法，改进了圆形度参数的定义。提出了计算机辅助植物识别(CAPI)的概念，并对其前景做了讨论和展望。图3参8     

Comment on "Opposing effects of native and exotic herbivores on plant invasions"

Parker et al. (Reports, 10 March 2006, p. 1459) showed that native herbivores suppress exotic plants more than native plants. Further analysis reveals that the effect of native herbivores is reduced on exotic plant species that are closely related to native species in the invaded region. Exotic plants may share traits with native congeners that confer similar resistance to resident herbivores.     

Starch accumulation associated with growth reduction at low temperatures in a tropical plant

Growth of Digitaria decumbens is severely reduced by night temperatures of 10 degrees C or below. Ultra-structure of leaves and chemical analyses show a high starch content in chloroplasts of plants illuminated and kept at a temperature of 30 degrees C. This starch disappears after a period in the dark at 30 degrees C, but it remains if the temperature during the dark period is 10 degrees C. The inhibition or slowing of starch translocation out of chloroplasts appears to account for reduced photo-synthesis and growth at low night temperatures.     

Rapid regulation of light harvesting and plant fitness in the field

We used Arabidopsis thaliana mutants to examine how a photosynthetic regulatory process, the qE-type or DeltapH-dependent nonphotochemical quenching, hereafter named feedback de-excitation, influences plant fitness in different light environments. We show that the feedback de-excitation is important for plant fitness in the field and in fluctuating light in a controlled environment but that it does not affect plant performance under constant light conditions. Our findings demonstrate that the feedback de-excitation confers a strong fitness advantage under field conditions and suggest that this advantage is due to the increase in plant tolerance to variation in light intensity rather than tolerance to high-intensity light itself.     

Abrupt decrease in tropical Pacific sea surface salinity at end of Little Ice Age

A 420-year history of strontium/calcium, uranium/calcium, and oxygen isotope ratios in eight coral cores from the Great Barrier Reef, Australia, indicates that sea surface temperature and salinity were higher in the 18th century than in the 20th century. An abrupt freshening after 1870 occurred simultaneously throughout the southwestern Pacific, coinciding with cooling tropical temperatures. Higher salinities between 1565 and 1870 are best explained by a combination of advection and wind-induced evaporation resulting from a strong latitudinal temperature gradient and intensified circulation. The global Little Ice Age glacial expansion may have been driven, in part, by greater poleward transport of water vapor from the tropical Pacific.     

几种热带苏木科观赏植物的引种观察

通过对引种成活的10种苏木科树种在温室内生长情况的初步观察,认为引种的大部分热带苏木科植物目前基本适应南京的温室环境条件,生长良好,有2种树已经开花结果,并有较好的观赏效果.对所引种的热带苏木科植物种类分布、生物学特性、观赏价值和引种后的生长情况作了系统介绍.     

麝香百合的叶片离体培养及植株再生

对麝香百合 (LiliumlongiflorumThunb)叶片进行离体培养 ,可成功获得无菌苗。试验结果表明 :培养基MS BA 0 1mg/L NAA 1 0mg/L适于初代培养 ,有助于根和芽的分化 ;MS BA 0 5mg/L NAA1 5mg/L适于增殖培养 ,利于愈伤组织的产生 ,并促进芽的分化 ;生根培养基为 1/ 2MS NAA 1 0mg/L 多效唑 10 0mg/L ;当试管苗根长 1cm时移栽易成活     

基于概率神经网络和分形的植物叶片机器识别研究

【目的】提出一种将植物叶片的形状特征与其纹理特征相结合的综合特征识别方法,有效解决了传统的植物机器识别分类特征单一且识别率较低的问题,为植物的快速机器识别提供技术参考。【方法】提取植物叶片样本的综合特征信息,以概率神经网络(PNN)为分类器对所得的特征信息进行训练,训练好的网络用来识别植物叶片的类别,从而确定相应植物的种类。【结果】有效提取了含有8个分量的植物叶片综合特征向量,通过对PNN分类器的训练,实现了30种植物叶片的快速机器识别,平均识别率达98.3%。比较测试表明,若去掉叶片纹理特征,单以其形状特征作为识别依据,平均识别率仅为93.7%。【结论】植物叶片综合特征识别方法有效弥补了传统单特征识别方法的不足,使识别效率得到了较大的提高。     

新加坡植物园热带园林植物景观营造分析

新加坡地理上位于赤道附近,具有独特的热带雨林气候,新加坡植物园位于新加坡城的核心区域,是以自然式为风致的热带风情植物园。园内分布有丰富的具有浓郁热带气息的园林植物景观,如:棕榈谷、热带雨林园、新加坡国家兰花园等景点,笔者通过对新加坡植物园内优美的园林植物景观进行分析,旨在探讨热带园林植物造景的一些手法和技巧,充实和丰富热带园林植物造景的相关理论和方法,以期能为我国热带及亚热带地区的园林植物造景提供一些启示。     

海南铜铁岭热带低地雨林植物区系研究

海南铜铁岭热带低地雨林的物种种类十分丰富,在2 600 m2的样地中有维管束植物88科、186属、258种.植物分布区类型组成,主产热带、亚热带的科占79.55%,热带分布属占旧世界分布属的95.08%;热带分布种占种总数的98.84%.热带分布的科、属中,以泛热带分布的科、属最多,分别占科、属总数的62.50%,28.49%.种的分布中以热带亚洲分布及其变型和中国特有成分占的比例最高,分别为55.43%和33.72%;分布至温带的科、属、种分别占科、属、种总数的19.32%,4.92%,1.16%.结果显示了铜铁岭低地雨林的热带北缘的性质.     

一种叶面遮盖剂在大豆灰斑病防治中的应用

为减少东北春大豆杀菌剂的施用量,在大豆灰斑病发病初期进行一种叶面遮盖剂喷施,研究其对大豆灰斑病的防控效果。以无人机喷施杀菌剂为施药对照,以不喷施任何药剂为空白对照。结果表明,喷施叶面遮盖剂对大豆灰斑病的防效达72.50%,同时有增产的效果,其增产率为16.00%。同喷施杀菌剂防控大豆灰斑病相比,叶面遮盖剂的使用更符合目前减施增效的农药使用政策。     

Toxicity of a furanocoumarin to armyworms: a case of biosynthetic escape from insect herbivores

When the linear furanocoumarin xanthotoxin, found in many plants of the families Rutaceae and Umbelliferae, was administered to larvae of Spodoptera eridania, a generalist insect herbivore, it displayed toxic properties lacking in its biosynthetic precursor umbelliferone. Reduced toxicity observed in the absence of ultraviolet light is consistent with the known mechanism of photoinactivation of DNA by furanocoumarins through ultraviolet-catalyzed cross-linkage of strands. Thus, the ability of a plant to convert umbelliferone to linear furanocoumarins appears to confer broader protection against insect herbivores.     

Colonization lessons from a tropical forest

The decade-old Transamazon Highway provides a useful stage for examining some of the major issues related to frontier conquest and the impact of pioneer settlement on one of the world's richest biomes. The highway project is an ambitious colonization scheme and the lessons that can be drawn from it, ranging from the environmental effects of stripping back the tree cover to the spread of diseases, will be useful in guiding development policy in other tropical regions.